A hydraulically controlled diaphragm pump for high pressures generally includes a thin metal diaphragm (made of stainless steel) which is deformable in its center in non-elastic manner, and which is disposed between a hydraulic control chamber and a working chamber. The amplitude with which the center of the diaphragm can be displaced is limited such that, other things being equal, obtaining a high flow rate requires the pump to operate at a high speed. This causes diaphragms to age fairly quickly, possibly leading to breakage so that the pumped fluid (which is generally aggressive) becomes mixed with the hydraulic chamber fluid which may rapidly destroy the pump itself in addition to putting it out of operation. It is therefore advantageous in this type of pump to provide two diaphragms so as to obtain more reliable isolation between the two fluids and to install a device for detecting diaphragm breakage.
Double diaphragm pumps exist with spacer material being placed between the diaphragms and provided with channels to allow a fluid coming from one or other of the pump chambers through a broken one of the diaphragms to flow towards a breakage detection duct formed in the pump body and facing the spacer material. Because of the high pressures used, such a technique cannot be transposed to metal diaphragms. The intermediate material is highly compressed between the two thin diaphragms during the delivery stroke of the pump and is then decompressed during the suction stroke, and as a result it is subjected to alternating stresses that are damaging to its strength over time and that cause it to deteriorate quickly.
The object of the present invention is to provide a solution suitable for detecting diaphragm breakage in a metal diaphragm pump by installing an intermediate material which withstands high compression well without significant deformation and without spoiling the operation of the pump, in particular without spoiling its degree of suction.